I'm making the plunge and picking up a 2.0GHz C2D Mac Mini after work today and it'll be my first Mac (it'll be the first Apple in my house since the Apple IIe ). I've just realised that I don't even know if it's able to do what I need in terms of its LAN connection. I need it to have two IP addresses. I have a device that when starting up needs to connect to an IP address and pick up a config file via TFTP, and then once this has completed its IP address changes and the IP address of the computer needs to change. To automate this I currently have a network card in a Windows XP PC that just always has two IP addresses, but do not know if it is possible under OS X on the Mac Mini. Does anyone know if this is achievable?

I guess my next step after this will be seeing if I can get the TFTP service configured to behave as I want... I was reading a 'learn the UNIX behind OS X' type book today in a store and it looked reasonable, and I have *nix experience so will hopefully be able to figure it out

Duh! The one place I hadn't thought to look was www.apple.com I think this might be what I'm looking for, http://docs.info.apple.com/article.html?path=Mac/10.5/en/15134.html - It only I hadn't found a possible solution at 9.30am, now I have to wait all day to get home and see if it works... and then once I get TFTP working how I want it I can finally turn off my Windows XP box and start turning it into a NAS

For anyone else that comes across this issue, ClunkClunk was on the money. I tried setting up a virtual interface under System Preferences > Network > That advanced settings gear icon thing > Manage Virtual Interfaces... but I was only able to choose the ethernet interface, when I needed to have it on my USB Ethernet adapter. So going back to ClunkClunk's suggestion, I just duplicated the USB Ethernet using System Preferences > Network > That advanced settings gear icon thing > Duplicate Service and set it up with the second IP address and it just worked... now I have the 100Mbit USB ethernet connecting to the network device that only has a throughput around 15Mbit and can use my onboard ethernet to connect to my fileserver at 1Gbit